The Effect of Raw Material Type on the Phase Composition in Aluminous Cements Containing Spinel

In this paper, the effects of dolomite type and Al2O3 content on the phase composition in the preparation of the aluminous cement containing MA spinel are investigated. For this reason, different compositions of raw and calcined dolomites are used as raw materials along with calcined alumina in the preparation of the aluminous cement containing MA spinel. Then, the compositions are prepared at 1350 °C using the sintering method and their mineralogical compositions are investigated using the diffractometric technique. Also, their microstructures have evaluated by SEM. The results indicate that raw materials used have great effect on the type and amount of formed phases in cement composition. Independently of the dolomite type used, a mixed phase product consisting of spinel accompanied by CA and CA2 is obtained. The content of CA phase in the cement composition is decreased with increasing of Al2O3 and therefore, decreasing of CaO in the raw materials composition. On the other hand, the CA2 content is increased with the addition of Al2O3. In addition, the results show that the formation of C12A7 is favored by use of calcined dolomite.